diff --git a/localized_fields/descriptor.py b/localized_fields/descriptor.py
index dd7000a..4d2babc 100644
--- a/localized_fields/descriptor.py
+++ b/localized_fields/descriptor.py
@@ -41,7 +41,7 @@ class LocalizedValueDescriptor:
 
         if self.field.name in instance.__dict__:
             value = instance.__dict__[self.field.name]
-        elif instance.pk is not None:
+        elif not instance._state.adding:
             instance.refresh_from_db(fields=[self.field.name])
             value = getattr(instance, self.field.name)
         else:
diff --git a/tests/test_field.py b/tests/test_field.py
index 3bd896c..de60523 100644
--- a/tests/test_field.py
+++ b/tests/test_field.py
@@ -1,6 +1,7 @@
 import json
 
 from django.conf import settings
+from django.db import models
 from django.db.utils import IntegrityError
 from django.test import TestCase
 
@@ -33,7 +34,6 @@ class LocalizedFieldTestCase(TestCase):
         field = LocalizedField(required=False)
         assert field.required == []
 
-
     @staticmethod
     def test_from_db_value():
         """Tests whether the :see:from_db_value function
@@ -205,6 +205,16 @@ class LocalizedFieldTestCase(TestCase):
         for field in field.formfield().fields:
             assert field.required
 
+    def test_descriptor_user_defined_primary_key(self):
+        """Tests that descriptor works even when primary key is user defined."""
+        model = get_fake_model(dict(
+            slug=models.SlugField(primary_key=True),
+            title=LocalizedField()
+        ))
+
+        obj = model.objects.create(slug='test', title='test')
+        assert obj.title == 'test'
+
     def test_required_all(self):
         """Tests whether passing required=True properly validates
         that all languages are filled in."""